FF/FS: Hot water cylinder+immersion, heating pump, 7-day heating controller

[Jonathan Larmour]

I recently changed my house central heating system and now have a number of items that are too useful to just bin. These would be useful as a cheap way for a DIYer to upgrade or renovate their existing heating system. Or just to keep as spares.

• Range Hercal foam-lagged 117l grade 3 indirect hot water cylinder including 3kW immersion heater. Cylinder size 900x450mm (NB excludes foam lagging). Suitable for gravity or pumped systems with working head up to 10m. Picture: of label: you can see there's also the sturdy table it came with, and a little pipework with the drain.

This website (not mine) has more technical details on it:

3 years old. System always had inhibitor. Worked perfectly for the little time we had it! New price: £186. Selling for £20 (but see bottom of post).

• Grundfos Selectric UPS 15-50 central heating pump. Selectable between three speeds. Includes isolation valves. Picture: installation leaflet.

This website (not mine) has more technical details on it:

4 years old. New price £59. Selling for £15.

• Drayton Tempus 7 central heating controller. 7 day programming, supports gravity-fed and fully pumped systems, easy-to-use, and very flexible, should be straightforward to swap with any older controller and trivial with another Tempus controller, about 6 years old but only appears to differ from existing Tempus 7 in fascia, in as-new condition.

- Pic of controller and instructions:

Pic of interface with flap down to program it A feeble attempt to show what's on the LCD display: wrote more about it in this cam.misc post: price: £58. Selling for £15.

For the cylinder and pump, buyer collects or arranges collection from east Cambridge, Cambs. For the heating controller, it is light enough to be posted in the UK for £2 P&P.

The e-mail address of this post works.

If you want any of the above items, but think I've not guessed a good selling price, mail me an offer anyway, including "I'd like it for free". If no-one else wants it at the asking price, you can have it!

If no-one asks, they go to the tip.

Jifl

[Set Square]

I hope that doesn't mean that you've thrown away a perfectly good hot water storage system and replaced it with a combi boiler! If you have, you may live to regret it - in which case I would hang on to the cylinder etc., ready for subsequent re-installation!

[Martyn Pollard]

Unfortunately that cylinder doesn't even meet Part L afaics. It has a BS date of 1984. The surface area of the coil is .44m2 and I would take that spec cylinder for scrap only - a few quid.

The grundfos pumps go for about =A35 secondhand on carboot sales and even some will barter down at that price, especially as there are signs of rusting on the valves :(

You might have some luck selling the controller on ebay for about a tenner.

Martyn

[Jonathan Larmour]

Set Square enlightened us with:

Alas it wasn't perfectly good as the previous back boiler was about 30 years old, and I was informed its cast iron heat exchanger was on its last legs. If I had got my arse into gear two years ago it might all have been cheaper.

But, for better or worse, it's been replaced by a condenser because as I'm sure a lot of uk.d-i-y knows, you now legally have to (unless there's some reason you can't, e.g. not being able to physically fit one). Although no doubt it's possible to find a certain type of plumber who'll fit whatever boiler you want anyway.

It's a Vaillant which at least has had good comments on uk.d-i-y, and I've had no complaints in the last, er, 3 weeks.

Prescott doesn't legally allow that now. IIRC the regs don't mention condensers explicitly, but give efficiency requirements that only condensers meet.

Jifl

[Jonathan Larmour]

Martyn Pollard enlightened us with:

Cylinders like that one go for up to £50 on eBay without even an immersion heater. I just want shot of it, not to make a big profit, so thought £20 would be better. You can make me an offer or say you'll take it only if it's free. That's fine as long as you arrange collection :-).

Normally they don't even come with the valves which are indeed much older than the pump itself, which is obvious to see really. But they were certainly working 100% in operation.

I just looked at eBay and they go (without valves) for £20-25, plus postage of ~9, so if you see them in car boots for a fiver you should snap it up and make a pretty profit on eBay!

Jifl

[Dave Plowman (News)]

You get condensing boilers for use with storage systems - ie not all are combis.

[Set Square]

You appear to be under the impression that 'condensing' and 'combi' are synonymous - which they ain't!

You are right about the current regs requiring you to have a condensing boiler. But that does *not* mean that you have to throw away your stored hot water system in favour of (allegedly!) "instant" hot water from a combi. It is perfectly possible to have a condensing boiler which provides stored hot water in addition to running the central heating.

[Jonathan Larmour]

Set Square enlightened us with:

I was, thanks (and also to the other poster) for the correction. While I knew not all combis were condensers, I had thought all condensers were combis. So what I really meant to say was that I've got a condensing combi :).

I can vouch for mine being instant other than the time to travel the length of the pipes. The difference being that it has a "warmstart" feature to address the very problem you're hinting at.

It seems that a boiler with warmstart will be much more efficient as it won't have to bring all of a 120l (or whatever) water cylinder up to temperature for an extended period of time; just the water within the (well-insulated) system inside the boiler. And at least for my model, it seems to work. So with that, a stored hot water system is no longer useful. Unless your boiler can't deliver the flow you need, although you'll eventually run out of stored hot water until it has time to catch up of course.

Jifl

[Dave Plowman (News)]

Fine if the flow is adequate. Which isn't the case from combis when filling a bath. Even the very best - and very expensive models - will be some 4 times slower to fill a bath than a well designed storage system. Most much, much more.

Then it's likely you don't have baths?

A fast recovery cylinder with a decent boiler can act like a modest combi, so never run out of hot water.

[Set Square]

I wasn't really talking about washing your hands so much as about running a bath. How long does it take to get a decent bathful of hot water compared with your previous system (assuming your now-discarded cylinder was hot to start with)?

In other words, once you've used up the combi's little store, at what rate can it generate further hot water?

[Vicky Larmour]

I'll butt in here since it's more commonly me that fills the bath so I'm in a better position than J to comment on the before/after situation. I would say that it takes *marginally* longer with the new system to fill the bath than it did before, but only very marginally.

And that is far outweighed (for us, I realise not necessarily for people with more predictable habits) by the benefits of not having to make sure there's enough hot water in the first place.

Vicky

[Jonathan Larmour]

I'm not sure what exactly you mean by "well designed". But I would have thought the only factors that will make any difference are the head of water and pipe diameter. IIRC we had half-inch pipes from the cylinder to the bath before. And header tanks in a pretty normal place in the loft somewhat raised on a platform, and bathroom on the first floor.

As a data point we have the Vaillant ecoMAX 828/2E which is 28kW. Obviously a less powerful boiler would have a slower flow rate. Dave, do you know the rating of the boiler(s) you've experienced before?

I will ignore derogatory comments elsewhere about my cleanliness ;), and make an observation that some of the other posters in this thread should be jolly careful lest their cleaning habits be published ;-P.

Jifl

[Dave Plowman (News)]

That's fine then. It sounds like your old storage system had poor flow for one reason or another, though.

[Jonathan Larmour]

Dave Plowman (News) enlightened us with:

Dunno, it seemed quite average (as in, typical), both in configuration and performance.

The new boiler's spec says the flow rate is 11.5l/min for a 35degC temp rise. Assuming an equal hot/cold mix, and an average bathtub capacity of 200l which you would want approx half full, that's just over 4 minutes to fill a bath.

The next boiler up in the range is 14.3l/min which would be 3 and a half minutes.

Doesn't seem that long to me, including from my experience of other peoples' and hotels' baths.

Jifl

[Dave Plowman (News)]

Right. You'd get poor flow with those - it should be 22mm or 3/4" in old money.

Sounds like the head should be OK. And again with a low pressure system you have to take more care with the pipework - bending the tube rather than using elbows, etc to minimise resistance.

[Dave Plowman (News)]

I doubt you'd want a 50/50 mix for a decent bath. ;-)

Well, I reckon on near that time with a hot flow of just under 25 l/min at

60C. So someone has the calculations wrong.

I've never seen a combi that can fill a bath with hot water in 3 or so minutes. I doubt the average mains water supply could fill one with cold in this time.

[Alan Braggins]

I'll happily collect for free if you don't get a better offer.

[Set Square]

Pretty dubious figures! Try these.

Cold water at 10 degC **, Mixed water at 40 degC (to allow for heating up the bath itself and giving a comfortable final temperature).

You'll have 11.5 l/m of hot water at 45 degC. To get a mix of 40 degC, you'll need SIX parts of hot to one of cold - i.e. about 2 l/m of cold - making a total flow of 13.5 l/m

I always thought that a decent bath required about 30 gallons - which is about 135 litres. You're thus looking at TEN minutes rather than four to achieve that.

[To get a 50/50 mix of hot and cold, the temperature of the cold would have to approach 25 degC - and I don't think it *ever* gets that high. You would then have a total flow of 23 l/m which your mains supply may well not be able to sustain].

** Reasonable average throughout the year - higher in the summer, and lower in the winter

[Jonathan Larmour]

Alan Braggins enlightened us with:

Someone's taking the heating controller, but no-one else wanted the cylinder or pump so it looks like they're yours!

Mail me to suggest some convenient time for collection, although evenings after 6.30 are most likely to work.

Jifl